MAST

MAST, (mât, Fr.) a long round piece of timber, elevated perpendicularly upon the keel of a ship, to which are attached the yards, the sails, and the rigging.

A mast, with regard to its length, is either formed of one single piece, which is called a pole-mast, or composed of several pieces joined together, each of which retains the name of mast separately. The lowest of these is accordingly named the lower-mast, a, fig. 1. plate VI. the next in heighth is. the top-mast, b, which is erected at the head of the former; and the higheft is the top-gallant-mast, c, which is prolonged from the upper end of the top-mast. Thus the two last are no other than a continuation of the first upwards.

Plate VI

The lower mast is fixed in the ship by an apparatus, described in the articles hulk and fixers: the foot, or heel of it, rests in a block of timber called the step, which is fixed. upon the kelfon; and the top-mast is attached to the head of it by the cap and the trestle-trees. The latter of these are two strong bars of timber, supported by two prominencies, which are as shoulders on the opposite sides of the mast, a little under its upper end: athwart these bars are fixed the cross-trees, upon which the frame of the top is supported. Between the lower mall-head, and the foremost of the cross-trees, a square space remains vacant, the sides of which are bounded by the two trestle-trees. Perpendicularly above this is the foremost hole in the cap, whose after-hole is solidly fixed on the head of the lower-mast. The top-mast is ereaed by a tackle, whose effort is communicated from the head of the lower mast to the foot of the top-mast; and the upper end of the latter is accordingly guided into, and conveyed up through, the holes between the trestie-trees and the cap, as above mentioned. The machinery by which it is elevated, or, according to the sea-phrase, swayed up, is fixed in the following manner: the top-rope d, fig. 2. passing through a block e, which is hooked on one side of the cap, and afterwards through a hole, furnished with a sheave or pully f, on. the lower end of the top-mast, is again brought upwards on the other side of the mast, where it is at length fastened to an eye-bolt in the capg, which is always on the side opposite to the top-block.e. To the lower end of the top-rope is fixed the top-tackle h, the effort of which being transmitted to the top-rope d, and thence to the heel of the top-mast f, necessarily lifts the latter upwards, parallel to the lower-mast. When the top-mast is raised to its proper heighth, fig. 3. the lower end of it becomes firmly wedged in the square hole, above described, between the trestle-trees. A bar of wood, or iron, called the sid, is then thrust through a hole i in the heel of it, across the trestle-trees, by which the whole weight of the top-mast is supported.